Ukraine and the West for months have accused Russia of supporting rebels in eastern Ukraine by sending in Russian troops, weapons and supplies. The United States and European countries have imposed economic sanctions on Russia over its involvement in Ukraine, while Russian officials have frequently denied claims their military has sent forces to bolster the rebels.

Yatsenyuk, according to Ukraine's state-run media, said Monday that his country's military "confirmed the fact military personnel and equipment have been transferred from Russia to Ukraine."

Read More

"Tanks, GRAD multiple rocket systems, BUK and SMERCH systems, radio electronic intelligence systems are not sold at local Donetsk street markets. Only the Russian army and Defense Ministry have them," Yatsenyuk said.

JUST WATCHED

At least 4,800 killed in Ukraine conflict

MUST WATCH

At least 4,800 killed in Ukraine conflict03:09

The prime minister's spokeswoman, Olga Lappo, confirmed to CNN the quotes attributed to Yatsenyuk are accurate.

Unrest in Ukraine began with protests in the country's capital last year after pro-Moscow President Viktor Yanukovych, favoring closer ties to Russia, dropped plans to sign a political and economic agreement with the European Union.

JUST WATCHED

Russia moving further into Ukraine is 'a possibility'

MUST WATCH

After months of protests and days of deadly clashes between demonstrators and security personnel in Kiev, Parliament ousted Yanukovych in February. Weeks later, Russia annexed the Crimean Peninsula.

In April, violence broke out in two Ukrainian regions that border Russia -- Donetsk and Luhansk -- as separatist leaders declared independence from the government in Kiev.

Pro-Russian separatists have claimed control of parts of Donetsk and Luhansk since the spring, despite a push by Ukrainian forces to defeat them. From mid-April to September 16 alone, at least 3,500 people were killed and at least 8,100 others were wounded in the conflict, according to the United Nations.